Http://kafila.org/what-are-the-causes-of-leaky-faucets/

• Loose or damaged faucet aerator: Over time, the aerator can become worn out or corroded, causing leaks around the faucet's handles.
• Mineral buildup and sediment: Hard water can leave behind deposits on the faucet's surfaces, which can restrict the flow of water and cause leaks.
• Clogged or restricted valves: Obstructions in the valve mechanisms can prevent water from flowing properly, leading to leaks.
• Worn-out O-rings and gaskets: Over time, these seals can become damaged or worn out, allowing water to seep into the pipes and cause leaks.

So, how do you fix a leaky faucet? The approach depends on the severity of the leak. Here are some general steps:

1. Turn off the water supply to the faucet by locating the shut-off valves under the sink and turning them clockwise.
2. Use a wrench or pliers to loosen any corroded or damaged O-rings or gaskets, and inspect the seals for signs of wear.
3. If there's mineral buildup or sediment, you may need to use descaling solutions or soak the faucet in vinegar and water to clear the deposits.
4. For more severe leaks, consider replacing the entire faucet cartridge or valve assembly.

By understanding the common causes of leaky faucets and taking steps to repair or replace them when necessary, you can save time, water, and money. Remember to always turn off the water supply before starting any maintenance work on your faucet.